The effect of ε-caproyl/d,l-lactyl unit composition on the hydrolytic degradation of poly(d,l-lactide-ran-ε-caprolactone)-poly(ethylene glycol)-poly(d,l-lactide-ran-ε-caprolactone)

Biomaterials ◽  
2006 ◽  
Vol 27 (4) ◽  
pp. 544-552 ◽  
Author(s):  
Hanjin Cho ◽  
Jeongho An
Keyword(s):  
Ethylene Glycol ◽  
Hydrolytic Degradation ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene

Mechanical properties and hydrolytic degradation of methoxy poly(ethylene glycol)-b-poly(DL-lactide-coglycolide- co-ε-caprolactone) diblock copolymer films

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Nongnit Morakot ◽  
Jirasak Threeprom ◽  
Yodthong Baimark
Keyword(s):  
Mechanical Properties ◽  
Weight Loss ◽  
Ethylene Glycol ◽  
Diblock Copolymers ◽  
Hydrolytic Degradation ◽  
Size Exclusion ◽  
Block Length ◽  
Poly Ethylene Glycol ◽  
Scanning Calorimetry ◽  
Poly Ethylene

AbstractBiodegradable films of methoxy poly(ethylene glycol)-b-poly(DL-lactideco- glycolide-co-ε-caprolactone) diblock copolymers (MPEG-b-PDLLGCL) were prepared by solution casting method. Effects of MPEG block length and DLL:G:CL ratio of the MPEG-b-PDLLGCL films on their mechanical properties and hydrolytic degradation were studied and discussed. It was found that the mechanical properties of films were strongly dependent on glass transition temperatures (Tg) of the diblock copolymers. The hydrolytic degradation was investigated in phosphatebuffered solution at 37°C. The degraded films were characterized using gravimetry (%water uptake and %weight loss), 1H-NMR spectroscopy, differential scanning calorimetry and size exclusion chromatography. The %weight loss of the degraded films increased and molecular weight decreased on increasing the MPEG block length and incorporating the G and CL units, according to their %water uptakes. The MPEG content of the degraded film decreased and the Tg increased with hydrolytic degradation time.

scholarly journals Instantaneous Degelling Thermoresponsive Hydrogel

Gels ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 169
Author(s):  
Noam Y. Steinman ◽  
Abraham J. Domb
Keyword(s):  
Lactic Acid ◽  
Controlled Release ◽  
Ethylene Glycol ◽  
Disulfide Bonds ◽  
Hydrolytic Degradation ◽  
Poly Lactic Acid ◽  
Hydrolytic Cleavage ◽  
Poly Ethylene Glycol ◽  
Thermoresponsive Polymer ◽  
Poly Ethylene

Responsive polymeric hydrogels have found wide application in the clinic as injectable, biocompatible, and biodegradable materials capable of controlled release of therapeutics. In this article, we introduce a thermoresponsive polymer hydrogel bearing covalent disulfide bonds. The cold aqueous polymer solution forms a hydrogel upon heating to physiological temperatures and undergoes slow degradation by hydrolytic cleavage of ester bonds. The disulfide functionality allows for immediate reductive cleavage of the redox-sensitive bond embedded within the polymer structure, affording the option of instantaneous hydrogel collapse. Poly (ethylene glycol)-b-poly (lactic acid)-S-S-poly (lactic acid)-b-poly (ethylene glycol) (PEG-PLA-SS-PLA-PEG) copolymer was synthesized by grafting PEG to PLA-SS-PLA via urethane linkages. The aqueous solution of the resultant copolymer was a free-flowing solution at ambient temperatures and formed a hydrogel above 32 °C. The immediate collapsibility of the hydrogel was displayed via reaction with NaBH4 as a relatively strong reducing agent, yet stability was displayed even in glutathione solution, in which the polymer degraded slowly by hydrolytic degradation. The polymeric hydrogel is capable of either long-term or immediate degradation and thus represents an attractive candidate as a biocompatible material for the controlled release of drugs.

Degradation Behavior of Poly(ethylene glycol) Diblock and Multiblock Polymers with Hydrolytically Degradable Ester Linkages

2004 ◽  
Vol 69 (8) ◽  
pp. 1643-1656 ◽  
Author(s):  
Alena Braunová ◽  
Michal Pechar ◽  
Karel Ulbrich
Keyword(s):  
Ethylene Glycol ◽  
Hydrolytic Degradation ◽  
Dicarboxylic Acids ◽  
Drug Carriers ◽  
Poly Ethylene Glycol ◽  
Model Study ◽  
Alkaline Conditions ◽  
Rate Of Hydrolysis ◽  
Poly Ethylene ◽  
The Stability

Diblock and multiblock polymers of poly(ethylene glycol) containing degradable ester bonds between the blocks were synthesized and characterized. Monofunctional poly(ethylene glycol) (PEG 2000) was modified by aliphatic dicarboxylic acids (malonic, succinic, glutaric, maleic) to obtain monocarboxylic polymers PEG-COOH containing ester bonds. Diblock polymers (4000) were prepared by polycondensation of a diamine (ethane-1,2-diamine, L-lysine) and the semitelechelic PEG-COOH. The relationship between the structure of the linkage connecting two PEG blocks and the rate of its hydrolytic degradation was studied at pH 5.5, 7.4 and 8.0. The rate of hydrolysis of all polymers was significant already under mild alkaline conditions (pH 7.4 and 8.0) and increased with increasing pH. The ester bonds of polymers with saturated dicarboxylic acid moieties were stable at pH 5.5. However, the presence of double bond in the acid moiety substantially decreased the stability of the polymer not only in alkaline but also in acid medium. The results of this model study can be utilized in the design of biodegradable high-molecular-weight drug carriers and polymers for preparation of "stealth" systems intended for therapeutic application.

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